1. Field of the Invention
Embodiments of the invention relate generally to the field of high magnetic field ohmically decoupled non-contact technology. More particularly, some embodiments of the invention relate to methods and apparatus for ohmically decoupled non-contact ultrasonic treatment of conductive materials via inductively induced surface current(s) in a static high magnetic field.
2. Discussion of the Related Art
Ultrasonic processing of materials in both the melt and solid phase is proving to be highly beneficial to material properties of metallic alloys. In the melt phase, acoustic treatment can be used to enhance diffusion, dispersion, and dissolution processes, resulting in improvements in the cleaning, refining, degassing, and solidification of the melt. Ultrasonic processing can be used to assist in grain refinement and to minimize segregation during solidification. Degassing with ultrasonics has resulted in reduced gas concentration, higher density, and improved mechanical properties. It has been demonstrated that non-dendritic structures can be produced with ultrasonic cavitation treatment, resulting in increased plasticity and enhanced strength. In the solid state phase, ultrasonic treatment could potentially be utilized to minimize residual stress, accelerate phase transformation processes, enhance nucleation and growth during phase transformations, enhance diffusive processes by enhancing the mobility of diffusing species, and enhance processes that have a threshold activation energy.
Commercially available ultrasonic processing systems require direct contact with the melt, resulting in undesirable chemical interactions when the acoustic probe/horn is inserted directly into the molten material or in direct contact with the containment vessel such as a crucible or mold. Ultrasonic transducers are limited in temperature range, and therefore must be thermally isolated from high-temperature environments through the use of an acoustical waveguide, or horn. Acoustic impedance mismatches between the transducer and the waveguide, as well as between the waveguide and the melt can limit the transfer of energy. Various types of probe coatings have been investigated in an effort to minimize the chemical interactions of the probe surface with the melt. In addition, the localized nature of the horn probe results in a very non-uniform distribution of acoustical energy within the melt crucible.
What is needed is a solution that (preferably simultaneously) solves the above described problems.